coasts Flashcards

Question

what is a joint

Answer 1

a fracture dividing rock into two sections that moved away from each other.

Answer 2

occurs when a stack of originally flat surfaces, such as sedimentary strata, are bent or curved as a result of permanent deformation

Answer 3

a crack in the Earth's crust. Typically, faults are associated with, or form, the boundaries between Earth's tectonic plates.

Answer 4

the acute angle that a rock surface makes with a horizontal plane

Answer 5

is the bending of a wave as it spreads over different depths, shallow water depths usually slow down the wave and the height increases In bays, wave crests curve to fill the bay and wave height decreases

Answer 6

the retreat of a coastline due to erosion, sea-level rise or submergence

Answer 7

erodes very slow have very few joints so there are limited weaknesses that erosion can exploit

Answer 8

erodes slow are often folded and heavily fractured which are weaknesses that increase erosion

Answer 9

erodes fast young rocks tend to be weaker with more bedding places and fractures more vulnerable to erosion

Answer 10

xerophytes (found in sand dunes)- can tolerate very dry conditions halophytes (can tolerate salt water) marram grass sea couch

Answer 11

are small ridges of sand found at the top of a beach, form from wind blown sand that is initially deposited against an obstruction. vegetation binds the sand together and stabilises the dunes

Answer 12

The first plants to grow in harsh coastal environments, paves way for other plants less able to survive in the conditions.

Answer 13

Flooded and drained by salt water brought in by the tides. the soil may be composed of deep mud and peat. peat is made up of decomposing plant matter that is often several feet thick and is waterlogged

Answer 14

Found in tropical locations along warm, shallow coasts. They are effective at reducing wave energy from tropical storms, cyclones, tsunamis. They are a natural coastal buffer to erosion and flooding

Answer 15

mangroves protect from erosion biological weathering with limited faults= more dfficult to erode deformation

Answer 16

are a medium through which energy is transferred They are created by the wind blowing across the surface of the sea. Frictional drag increases as the wind speed increases, making the wave bigger.

Answer 17

the distance a wave travels the maximum fetch is the distance from one coastline to the next landmass

Answer 18

when constructive waves are more common than destructive the swash of a constructive wave deposits larger material at the top of a beach creating a berm as it builds up the backwash becomes weaker.

Answer 19

berms are eroded by plunging waves and high-energy swash strong backwash transports sediment offshore

Answer 20

hydraulic action, corrosion, abrasion, attrition

Answer 21

Air trapped in cracks and fissures is compressed by the force of waves crashing against the cliff face. Pressure forces cracks open, meaning more air is trapped and greater force experienced in the next cycle of compression.

Answer 22

Carbonate rocks (limestones) are vulnerable to solution by rainwater, spray from the sea and seawater.

Answer 23

Sediment picked up by breaking waves is thrown against the cliff face. The sediment acts like a tool on the cliff, chiselling away at the surface and gradually wearing it down by removing small rock particles.

Answer 24

This process acts on already eroded sediment. As sediment is moved around by waves, the numerous collisions between particles slowly chip fragments off the sediment.

Answer 25

wave type and size and lithology

Answer 26

* hydraulic action and abrasion are most dominant * the lithology bands of more resistant rock between weaker joins and cracks erode more slowly. This selective erosion is known as differential erosion.

Answer 27

wave cut notches, wave cut platforms, cliffs, the cave-arch-stack stump sequence

Answer 28

eroded at the base of a cliff by hydraulic action and abrasion, as the notch becomes deeper, the overhanging rock above becomes unstable and eventually collapses as a rockfall. repeated cycles of notch cutting and collapse cause cliffs to reduce inland

Answer 29

the former cliff position after wave cut notches occur and is horizontal rock platform Slopes gently down to the angle of 3-4 degrees. An overall pitted appearance of bare rock interspersed with rock pools. Bare rock, smoothed in places by abrasion. Deep cracks in some places. Covered at high tide and exposed at low tides.

Answer 30

1.Destructive waves erode the cliff through processes such as abrasion and hydraulic action 2.Waves erode the cliff between the high and low tide lines. 3.Over time, this erosion creates a wave cut notch at the base of the cliff. 4.This notch gradually gets larger. The cliff above the wave cut notch is now unsupported 5.Mass movement (falling of material) occurs as a result of gravity and the cliff retreats. 6.The wave cut platform is the uneroded section of the original cliff at the base. 7.the process repeats and cliff continues retreating

Answer 31

traction, saltation, suspension, solution

Answer 32

bigger pebbles and boulders are rolled along the sea bed

Answer 33

small pebbles moved when one pebble hits another, making it bounce. This bouncing sets up a chain reaction

Answer 34

fine sediment is carried as suspension in the water, this is what makes water look dirty.

Answer 35

dissolved material is carried along and you can’t see it. (invisible)

Answer 36

the swash moves beach sediment up the beach at the same angle as wave approaches. the backwash of wach wave then carries the same sediments back down the beach at right angles to the shore

Answer 37

wave crests break at an angle to the coast, so there is consistent longshore drift

Answer 38

wave crests approach parallel to the coast, so there is limited longshore movement of sediment.

Answer 39

is a depositional process that is important for very small particles, such as clay, which are so small they remain suspended in water. Clay particles clump together due to electrical or chemical attraction and become large enough to sink.

Answer 40

occurs when the energy of transporting water becomes too low to move sediment; large sediment will be deposited first

Answer 41

beaches, recurved and double spits, offshore bars, barrier beaches and bars, tombolos and cuspate forelands

Answer 42

* Storm beaches are a ridge of boulders and shingle found at the back of a beach They result from high energy deposition at high tides or during severe storms. They are found on the backshore * Beach cusps are crescent shaped indentations that form on beaches of mixed sand and shingle- located in low energy bays

Answer 43

sand or shingle is moved along the coast by longshore drift,but if the coastline suddenly changes direction then sediment will begin to be deposited and built up. the outward flow of the river will prevent the spit from extending the full width of the estuary. behind the spit a lagoon forms and sediment is deposited there and eventually builds up to sea level to form a salt marsh

Answer 44

occasionally a storm comes in and causes the direction of the prevailing wind to change and moves sediment in a different direction forming the curve or hook when wind direction returns to normal the spit resumes its growth.

Answer 45

formed from a breach of a pre existing spit or bar usually by a river or storm

Answer 46

form in the same way as a spit initially but bars are created where a spit grows across a bay, joining two headlands. Behind the bar, a lagoon is created, where water has been trapped and the lagoon may gradually be infilled as a salt marsh develops due to it being a low energy zone, which encourages deposition.

Answer 47

These can be formed by rising sea level when a barrier beach becomes separated from the mainland forming a ridge or island.

Answer 48

also known as sandbars are submerged or partly exposed ridges or coarse sediment. They are created by waves that operate offshore from the coast. destructive waves erode sand from beach and swash which removes sediment and deposits it offshore as bars

Answer 49

a beach formed between a small island and the mainland and deposition occurs where waves lose energy and tombolo builds up * Waves are refracted around the island & set up 2 opposing LSD directions. * These merge behind the island & sand is deposited linking the mainland & the island

Answer 50

is a triangular-shaped headland that extends from main coastline * They form where the coast is exposed to longshore drift from opposite directions * Sediment is deposited at the point where they meet and forms a natural triangular shape * Vegetation eventually grows and stabilises the sediment.

Answer 51

mechanical, chemical, biological

Answer 52

is the breaking down of rock into smaller particles. Weathering processes include freeze thaw action, acid rain dissolution, root growth, heat expansion cracking

Answer 53

occuring or formed in the open air include weathering and mass movement. operate on the cliff face to weaken it and provide material for coastal erosion

Answer 54

* caused by physical changes such as changes in temperature, freezing and thawing, and the effects of wind, rain and waves.

Answer 55

temperture- When a rock gets hot it expands a little, and when a rock gets cold it contracts a little. If a rock is heated and cooled many times, cracks form and rocks fall away

Answer 56

Water expands slightly when it freezes into ice. so as it gets into cracks in rocks and freezes it causes crack to expand and rock breaks off

Answer 57

* when salt crystals are deposited in cracks and over time the salt accumulates and applies pressure to the crack * wet rocks may expand (clay) and contract when dry causes cracks and vulnerable to freeze thaw and salt crystalisation

Answer 58

speeds up mechanical and chemical weathering throught the action of plants, bacteria or animals root boring occurs when clams and molluscs bore into rock and may also secrete chemicals that dissolve rocks

Answer 59

* involves decomposition of rocks changing the minerals occurs as a result of a weak chemical reaction between water and rock * Rainwater mixed with carbon dioxide in the atmosphere forms Carbonic acid. This then reacts with calcium carbonate in limestone to form calcium bicarbonate. Bicarbonate is soluble in water and the limestone gets weathered when carbonation occurs. * The breakdown of minerals to form new clay minerals plus materials in solution * The addition of oxygen to minerals which produces iron oxides and increases volume which contributes to mechanical breakdown.

Answer 60

the down slope movement of earth materials under gravity 1. rock falls 2. translational slides 3. rotational slumping 4. topples 5. flows

Answer 61

when strong jointed and steep rock faces are exposed to mechanical weathering. Occur on slopes over 40 degrees. the material either bounces or falls vertically to form scree

Answer 62

rocks that are jointed or have bedding planes roughly parallel to the slope or cliff surface are susceptible to landslides. an increase in the amount of water can reduce friction- causing sliding in a rock or landslide, slabs or blocks can slide underlying rocks along a slipe plane or slide.

Answer 63

in saturated conditions, slip on moderate to steep slopes common where softer materials overlie more resistant or impermeable rocks (limestone) causes rotational scars on the land and repeated slumping causes terraced cliff profiles they leave marks on the landscape known as rotational scars

Answer 64

the is influenced by the geological structure of the rock face where rock strata have a steep seaward dip, undercutting by erosion will quickly lead to instability and blocks of material falling seawards

Answer 65

an increase in the amount of water can reduce friction and cause mud and earth to flow over the underlying bedrock the difference between a slide and a flow is that in a slide the material remains intact in a flow it becomes jumbled up.

Answer 66

terraced cliff profile

Answer 67

due to high and low tides Atmospheric air pressure (low pressure causes slight rise in sea level) Winds which can push water towards the coast and wave heights which vary

Answer 68

eustatic change isostatic change

Answer 69

Global-scale sea level change caused by a change in the volume of water in the ocean store Heating of ocean water causes the water molecules to move, The free movement of these particles causes the expansion of liquid.

Answer 70

Local-scale sea level change caused by a change in the level of the land relative to the level of the sea.

Answer 71

emergent coasts- where the coasts are rising relative to sea level, for example due to tectonic uplift Submergent coasts – are being flooded by the sea, either due to rising sea levels and/or subsiding land

Answer 72

When the weight of an ice sheet on land causes it to sink, this give the appearance that the sea has risen. | eg Scotland

Answer 73

When the ice melts the reduced weight causes the land to readjust and rise, this can give the appearance that the sea level is falling. | eg england+ wales

Answer 74

a raised beach- areas of former wave-cut platforms and their beaches left at a higher level than present sea level due to sea level change. They are found at a distance inland from the present coastline.

Answer 75

raised beaches- little Gruinard (NW scotland) abandoned cliff line- Kings cave (have caves cut by marine erosion but are now left higher and dry + unaffected by marine erosion

Answer 76

Ria- are submerged river valleys- lowest part of the river's coarse and the floodplains may be completely drowned but tops of valley course remain exposed (Kingsbridge Ria- south devon) Fjord- are submerged glacial valleys- have very steep sides and the water in a fjord is very deep (Milford Sound- New Zealand) Barrier islands- formed initially as lines of coastal sand dunes attatched to the shore. sea level rise floods the land behind form a lagoon, leaving the dunes as islands (East coast of America) Dalmation coasts- form where there are hills running parallel to the coast. rising sea levels submerge the area to create long narrow islands arranged in lines. ( dalmation coast-Croatia) tectonic activity raised beaches- a series of storm beach ridges. The ridge very close to the shore is the present storm beach ridge. then there is previous inland ridges (New Zealand)

Answer 77

human- dredging, dams or coastal management eg groynes physical- geological eg softer= vulnerable to mass movement weathering and erosion, marine eg long wave fetch, strong longshore drift erode debris quickly

Answer 78

* average it loses 2m of a coastline every year * lack of physical protection of cliffs by narrow and low beaches * has boulder clay that can easily be eroded

Answer 79

erosion rates increase further down variation in cliff height

Answer 80

deep hollows on the beach which run parallel to teh cliff line- they concentrate erosion in particular locations by allowing the waves to directly hit the cliff with little energy dissipation on the beach they erode 4x faster than areas withour ORDS

Answer 81

* coastlines are popular with tourists, especially when access to beaches and the sea is easy * deltas and esuaries are ideal locations for trade * delatas are especially fertile and ideal for farming

Answer 82

* sediment trapped by upstream dams, reduce new deposition on delta surface * sea level rise increases flood risk and erosion storm surges from hurricanes flood the delta more frequently * delta subsidence is caused by weight of sediment deposition, which balanced on the delta surfaces * destruction of mangrove forests for wood and charcoal exposes the coast to erosion * river straightening for navigation means faster river flow and sediment being propelled too far offshore

Answer 83

is a short-term change in sea level caused by low air pressure which can be a depression, or a tropical cyclone

Answer 84

low pressure weather system in the mid-latitides, eg uk

Answer 85

* strong winds push waves onshore, so wave height increases * high or spring tide occur at the same time as the storm * sea bed shallowes towards the coast

Answer 86

when the coastline is funnel-shaped and causes severe coastal flooding

Answer 87

* dams * urbanisation * deforestation

Answer 88

* isostatic * eustatic * low lying delta * topography * cyclone/storm surge

Answer 89

* sea level rising * 50% increase in delta flooding * strorm surges linked to depressions will become more common * higher erosion

Answer 90

adaptation- making changes to lessen the impact- include building sea walls, storm surge barriers, reinstating mangrove forests mitigation- making efforts to reduce the emissions of greenhouse gases- finding alternative renewable sources of energy, cleaner industry, hybrid/electric cars, housing insulation, turning off lights etc

Answer 91

causes= Lithology; Geological structure; waves; human intervention. social=Impacts on people - costs of relocation; employment; businesses and agricultural land. Mental health - stress and worry linked to recession - Hard to quantify. Loss of amenity value. economic=Costs of; businesses and agricultural land. Repairs e.g. roads, trains.

Answer 92

causes=Cyclones; Storm surges; SL rise; urbanisation; deforestation (mangroves) social= Loss of homes; loss of life; people homeless. Stress and bereavement etc. economic= Loss of land; damage to homes and infrastructure. Economic losses (wages).

Answer 93

loss of or damage to property in form of homes, businesses and farmland is easy to quantify in Uk gov dont provide compensation to people who lose their homes to coastal erosion

Answer 94

relocation break up of community loss of friends stressful source of income

Answer 95

are those forced to leave their homes because of natural processes, including sudden ones such as landslides or gradual ones such as erosion or rising sea levels predicts sea level rise by 2100 would leave envir refugees due to flooding, salt water encroachment, coral bleaching

Answer 96

a very expensive (over US$1 billion), technically difficult and usually long-term engineering project. Have multiple aims

Answer 97

Refers to the frequency of a flood of a particular magnitude. A 1:100 flood event will occur, on average, every 100 years

Answer 98

hard engineering- using artificial structures to defend land against natural erosion processes soft engineering- by working with natural processes to help restore beaches / ecosystems and reduce erosion. mitigation- to manage the coastal zone in terms of people’s economic/social/cultural well being as well as minimising environmental impacts. It encourages communities to adapt to the threats

Answer 99

1. groynes 2. sea walls 3. rip rap 4. revetmentsz 5. offshore breakwaters

Answer 100

ad- maintain the size of a beach protects coast at the point. enhance the beach enhance tourism less expensive than sea walls dis-expensive due to difficulties in getting firm foundations in a beach. may be an obstacle to people moving along a beach not natural so could be eyesoar greatly reduce longshore drift transport may cause narrower beaches and increased erosion down drift

Answer 101

ad- made of long lasting concrete and able to absorb wave energy give people confidence and a sense of security the tops can be used as promenades dis- most expensive do not fit in with natural surroundings accessing beach may be difficult

Answer 102

ad- long lasting and flexible to use placed at susceptible points on the backshore to protect base of sea wall or groyne dis- maylool unsightly can create difficult access as difficult to climb over seawater can move through it so some weathering and erosion may still occur ## Footnote (boulders concrete shapes)

Answer 103

ad- absorb wave energy trap beach sediment behind them longshore drift can continue cheaper to sea walls dis- reduce access to beach looks unsightly may need constant maintenance ## Footnote are sloped walls often made of wood

Answer 104

ad- proved effective create sheltered water areas behind them for water sports and tourism used to protect entrance to harbours dis- look unsightly may need olther coastal engineering create increased deposition on the landward side ## Footnote rock boulders (usually granite) dropped and aligned in short lengths in shallow nearshore waters parallel to the shore

Answer 105

1. beach nourishment 2. cliff regrading (cut the cliff slope to a stable angle) 3. cliff drainage (when cliff lithology consists of a permeable layer above impermeable layer: drains with gravel can be inserted to drain water out fast) 4. dune stabilisation (replant grass)

Answer 106

Managing the wider coastal zone in terms of people and their economic livelihoods, social and cultural well-being, and safety from coastal hazards, as well as minimising environmental and ecological impacts.

Answer 107

* managing natural resources= long term productivity * managing flood and erosion risk/ relocating to safe areas * create alternative livelihoods before existing ones are lost * adapting to rising sea levels by relocating alternative building methods * educate communities * monitering coastal change and adapt to unexpected trend

Answer 108

coastal management must: * plan for the long term * involve all stakeholders * adopt ‘adaptive management’, changing plans and policies if threats change * try to work with natural processes, not against them * use ‘participatory planning’ where all stakeholders have a say in any policy decisions.

Answer 109

there are 11 is managed either as a whole unit or a sub-unit and a shoreline management plan (SMP) is used

Answer 110

1. hold the existing shoreline 2. advance the existing shoreline 3. managed realignment of the shoreline 4. no active intervention

Answer 111

engineering feasibility environmental sensitivity land value political and social reasons cost benefit analysis (CBA) environmental impact assessment (EIA)

coasts Flashcards

(135 cards)